The invention relates to the field of ice protectors for inhibiting atmospheric ice accumulation on aircraft structures. More particularly, the invention relates to the bonding of an ice protector to an aircraft structure.
Atmospheric ice accumulation on the ground and in flight has long been recognized as a serious hazard. Various de-icing and anti-icing devices have been developed to safely remove or prevent unwanted ice accumulations on the external surfaces of aircraft. Many of these devices comprise flexible ice protectors that are bonded to existing external surfaces using a removable adhesive. An ice protector based on this concept may thus be removed and replaced if it fails or becomes damaged. A very common adhesive used for this purpose is catalogue number 1300L available from the Minnesota Mining and Manufacturing Company, St. Paul, Minn., U.S.A. Previous ice protectors that have been applied in this manner include elastomeric pneumatic de-icers, elastomeric electrothermal de-icers and anti-icers, and some electromechanical de-icers.
Installation of an ice protector using an adhesive such as 1300L involves applying the adhesive to the aircraft structure and to a bonding surface of the ice protector. The adhesive is permitted to dry and then activated by wiping it with a solvent such as toluene or methyl-ethyl-ketone (MEK). The adhesive behaves as a contact adhesive, and the ice protector is then pressed against the aircraft structure beginning with a selected area (such as a leading edge) and subsequently with increasing distance from the selected area. Rollers are preferably used to insure intimate contact between the two adhesive layers.
In spite of the wide-spread acceptance of this prior technique, a stronger and more durable adhesive interface between the ice protector and the aircraft structure is generally desired. The adhesive interface must withstand attacks of sun, rain, de-icing fluids, hydraulic fluids, turbine oils, and other degrading elements. In addition, prior commonly used adhesives have a very limited shelf life, and often contain toluol and MEK, as well as other potentially toxic chemicals. Various government agencies have placed severe restrictions on methods of shipping these adhesives, and on how the adhesives and solvents may be used. Finally, prior adhesives require several hours to cure before the ice protectors may be activated. Imposing several hours downtime on commercial operators is undesirable.
Though prior adhesives are certainly safe and suitable for attaching ice protectors to aircraft structures, an adhesive having more desirable characteristics is desired. In particular, a strong and durable adhesive with good environmental resistance is generally desired. An adhesive having longer shelf life, and not containing or requiring use of solvents in the field is generally desired. Finally, an adhesive that bonds an ice protector in a manner that immediately allows the ice protector to be operated is desired. The specific problem at hand is to provide a self-adhering flexible ice protector having the enumerated adhesive characteristics.
According to an aspect of the invention, a device is provided for inhibiting atmospheric ice accumulation on an aircraft structure, comprising:
a flexible ice protector;
an intermediate layer bonded to the flexible ice protector, the intermediate layer having a lesser modulus of elasticity than the flexible ice protector;
a pressure sensitive adhesive layer bonded to the intermediate layer, the pressure sensitive adhesive layer defining a bonding surface that bonds to the aircraft structure.
According to another aspect of the invention, a device is provided for inhibiting atmospheric ice accumulation on an aircraft structure, comprising:
a flexible ice protector;
an intermediate layer disposed between the flexible ice protector and the aircraft structure;
an intermediate adhesive layer bonding the intermediate layer to the ice protector, the intermediate layer and the ice protector being comprised of different materials adjacent the intermediate adhesive layer, the intermediate adhesive layer being particularly suited to bond the intermediate layer to the ice protector;
a pressure sensitive adhesive layer that bonds the intermediate layer to the aircraft structure, the pressure sensitive adhesive layer being particularly suited to bond the intermediate layer to the aircraft structure.
According to yet another aspect of the invention, a method is provided for attaching a flexible ice protector to an aircraft structure, comprising the steps of:
bonding the flexible ice protector to the aircraft structure by means of an intermediate layer bonded to the ice protector, the intermediate layer being more compressible than the ice protector and having a pressure sensitive adhesive layer on a side of the intermediate layer opposite the ice protector that bonds the intermediate layer to the aircraft structure.
The invention provides a self-adhering ice protector having a strong and durable adhesive with good environmental resistance. It provides an adhesive having longer shelf life than prior adhesives, and that does not contain or require use of solvents in the field. Finally, the invention provides an adhesive that bonds an ice protector in a manner that immediately allows the ice protector to be operated.